Polymers of alkoxy alkyl acrylates, alkyl acrylates and substituted norbornene

ABSTRACT

Acrylate elastomers having an improved retention of abrasion resistance after oil immersion, which are readily vulcanized, are prepared with 9 to 59 percent by weight alkoxy alkyl acrylate, 40 to 90 percent by weight alkyl acrylate and about 0.5 to 5.5 percent by weight substituted norbornene compounds.

United States Patent Starmer [451 Oct. 10, 1972 [54] POLYMERS OF ALKOXYALKYL 2,768,080 10/1956 Hellmann et al. ..260/80.76 ACRYLATES, ALKYLACRYLATES 3,036,976 5/1962 Sanderson ..260/80.76 AND SUBSTITUTEDNORBORNENE 2,985,611 5/1961 Gaylord et al.. ....260/80.75 3,098,8357/1963 Gaylord ..260/80.75 [72] invent Lake Ohm 3,249,651 5/1966 Gaylord..260/80.76 [73] Assignee: The B. F. Goodrich Company, New 3,520,843 7/1970 Moody et al ..260/80.81

York, NY. Primary Examiner-Harry Wong, Jr. [22] Flled June 1971Attorney-Albert C. Doxsey et a1. [21] Appl. No.: 155,243

[57] ABSTRACT [52] US. Cl. ..26 0/80.76, 260/29.6 T, 260/41 C, Acrylateelastomers having an improved retention of 260/45.7, 2601459, 260/45.95,260/79.5 P, abrasion resistance after oil immersion, which are 260/86.lR, 260/487 readily vulcanized, are prepared with 9 to 59 percent [51]Int. Cl ..C08f 15/16, C08f 15/18 by weight alkoxy alkyl acrylate, 40 to90 percent by [58] Field of Search ..260/80.75, 80.76 weight alkylacrylate and about 0.5 to 5.5 percent by weight substituted norbomenecompounds. [56] References Cited UNITED STATES PATENTS 7 Claims, NoDrawings POLYMERS OF ALKOXY ALKYL ACRYLATES, I

ALKYL ACRYLATES AND SUBSTITUTED NORBORNENE BACKGROUND OF THE INVENTIONU.S. Pat. No. 3,536,681 shows that substituted-norbornene compounds,resulting from the reaction of 2- hydroxymethyl-Snorbornene with acidhalides and esters of organic acids, react with alkyl acrylates toprovide cure sites for vulcanization of the polyacrylates in thesoap-sulfur system. Thesecured polyacrylates have good flex strength,ozone resistance, and resistance to oil. They are useful .for gaskets,hose, wire insulation, coatings and the like. The polymers shown in thepatent have a fair balance of properties, but it would be desirable toprepare polyacrylates for cure that have an even higher levelof abrasionresistance after oil immersion. Manufacturers of oil seals desire thatthe seals swell a maximum of 25 percent in oil at conditions ranging toas low as about 25 C.

SUMMARY OF THE INVENTION Acrylate elastomers containing cure sitesderived from substituted 2-hydroxymethyl-5norbornene compounds areobtained by-polymerizing together 9 to '59 percent by weight alkoxyalkyl acrylate, 40 to 90'percent by weight alkyl acrylate and about 0.5to 5.5 percent by weight substituted Z-hydroxymethyl-S-norbornene.

Substituted norbornene compounds useful in this invention includereaction products of 2-hydroxymethyl- 5-norbornene with acid halides oresters of alphachlorinated or alpha, beta-chlorinated fatty acids. Theacids containing one to ten carbon atoms may be used butalpha-chlorinated derivatives of acetic, propionic, butyric and valericacids are preferred. The acid may be reacted with an alcohol, preferablymethanol, ethanol or p'ropanol to form the corresponding ester beforereacting with the 2-hydroxymethyl-5norbornene.

The substituted norbornenes have the structure where n is either zero or1, R is and R is either hydrogen or halogen, but if n. is zero, then Ris halogen. These substituted norbornene compositions copolymerize withother'monom'ers including the acrylates and provide sites for elastomercures.

Useful alkoxyl alkyl acrylates present in the copolymers of theinvention in amounts from 9 to 59 percent by weight and replacing aportion of the alkyl acrylate moiety shown in theprior art arerepresented by the formula wherein R, is an alkylene radical containingone to four carbon atomsand R is an alkyl radical containing one to fourcarbon atoms or'an alkoxyalkyl radical. Particularly useful are alkoxyalkyl acrylates wherein R is--- CH or CI-I CH and R is methyl, ethyl,methoxy ethyl or'ethoxy ethyl. Typical alkoxy acrylates includemethoxyethyl acrylate, methoxymethyl acrylate, ethoxyethyl acrylate,butoxyethyl acrylate, and methoxyethoxyethyl acrylate. An optimumretention of abrasion resistance after oil immersion has been obtainedwith methoxyethyl acrylate. The amount of alkoxy alkyl acrylate employedis preferably 9 to 59 percent by weight of total monomers. Lower rangesoffer no aid to oil swell resistance and higher ranges detract from-heatresistance.

The acrylic elastomers of this invention contain from 40 to percent'by'weight of total monomers of acrylic acid esters having the structure HCHr=C-C 0 OR haveglass or second order transition temperatures of below0 C.. In addition to having excellent abrasion resistance after oilimmersion these elastomers have a good balance of oil swell resistanceand low temperature flexibility plus good resistance to heat. Theinterpolymers are prepared by methods used by those skilled in the artin providing acrylic elastomers. Such polymerizations may be conductedin bulk or in solution, but the preferred method is to polymerize themonomers in water or in an aqueous dispersion. Polymerization maybeconducted in batch reactions or the monomers may be proportioned to areactor containing water and other desired polymerization additives.Polymerizations may be conducted at l0 to C. Best results are generallyobtained at temperatures in the range of 5 to 50 C in the presence ofwater containing a free radical generating catalyst and surface activeagents.

The catalyst employed may be any of those free radical forming and othercatalysts known to those skilled in the art including both organic andinorganic .peroxide, inorganic persulfates, organic hydroperoxides, azocompounds, the well known redox catalyst systems, and reduced metalcatalysts. Other additives to the water will includeacids or bases toadjust the pH of the aqueous dispersion which usually is in the range ofabout4 to 8; buffers, inorganic salts and surface active agents. Sincesome of the alkyl acrylates are soluble in water only minimum amounts ofsurface active agents are normally required to form polymers. Largeramounts normally will be employed when stable latices are desired. Suchsurface active agents may include anionic, cationic and non-ionicmaterials. Typical surface active agents founduseful in preparing theinterpolymers include sodium alkyl sulfates as sodium lauryl 3 sulfates,sodium .alkyl aryl I sulfonates, sodium naphthalene sulfonate,quaternary salts, polyglycol fattyacid esters and the like. As isobvious, the

The resulting dried elastomers may contain or have I added theretostabilizers which are effective as antioxidants and antiozonants, and inmany cases improved heat resistance of the elastomers is obtained by useof such stabilizers and organic phosphites. Use of both phosphites andother antioxidants as the phenol derivatives is suggested. The usualantioxidants and stabilizers may be added to the rubber in latex state,milled or in cements. Aryl phenols are preferred as they arenonstaining, but aryl amines may be used. Age resistors andantioxidants-of the known type such as octylated diphenylamines,styrenated phenols, polyalkyl polyphenols, PBNA, and others, may beused.

The novel polymers of this invention may be compounded with a variety ofvulcanizing agents. Examples of the vulcanization systems which can beused with these acrylic elastomers are fatty acid soaps and dipentamethylene thiuram .hexasulfide, fatty acid soap and sulfur,hexamethylene diamine, triethylene diamine, ammonium benzoate, ammoniumadipate, ammonium stearate, dicyandiamide with azela ic acid and thelike. Also useful for special compounds are plasticizers, softeners, andtackifiers; and reinforcing pigments, for example, the various carbonblacks, both channel and furnace, inert'fillers and diluents. Allmay beused as will be understoodby those skilled in the compounding art. I

DETAILED DESCRIPTION OF THE INVENTION EXAMPLE I.

PREPARATION OF SUBSTITUTED 2- I-IYDROXYMETHYL-5-NORBORNENE A SOO-ml.three-necked round bottom flask is fitted with thermometer, refluxcondenser, dropping funnel and, agitator. The reaction medium, 150 ml.of benzene, and,39.8 g. (0.443 mole) of 2-hydroxymethyl 5-norbornene areadded and cooled at 15 C. Next 44.7 g. (0.443 mole) of triethylamine ischarged, and then 50 g. (0.443 mole) of chloroacetyl chloride is added.dropwise. The reaction mixture is warmed to room temperature and standsfor 2 hours. It is filtered to remove solid triethylamine hydrochloride,which is washed with benzene. The benzene solution is washedconsecutively with dilute hydrochloric acid, dilute sodium bicarbonate,and distilled water, then dried over anhydrous magnesium sulfate. Thebenzene is removed by distillation under reduced pressure. Finally theproduct is fractionally distilled.

.4" The 5-chloroacetoxymethyl-2-norbornene has a boiling point of 69 72C. at- 0.2. mm. Analysisfor chlorine is 17.6 weight percent; theoreticalweight per- .cent chlorine-is 17.7 percent. The'Nuclear MagneticResonance (NMR) spectrum is consistent with the formula set forth abovewhere n 0, and R is C].

EXAMPLE 2 Av series of copolymers is prepared with the monomers setforth in the data table below according to a polymerization recipeusing, in parts by weight, of water, 2.0 alkyl phenoxypoly (ethyleneoxy) ethyl ester of phosphoric acid, 0.1 sodium hydroxide,

0.01 of the sodium ferric salt ethylene-diarriine tetraacetic acid,100.0 of monomers, 0.3 of sodium salt of polymerized naphthalenesulfonic acid, 0.024 tetrasodium ethylene diamine tetraacetate, 0.3sodium sulfate, 0.02 sodium hydrosulfite, 0.04 sodium formaldehydesulfoxylate, and-0.04 cumene hydroperoxide. The reaction is conducted at30 C and the monomers are proportioned into the reactor over a 2 hourperiod. The initial pH of the water-emulsifier mixture is between 6 and7. Polymers are coagulated with calcium chloride solution, washed, anddried.

Example 2 3 4 v 5 6 Ethyl acrylate 98 49.1 48.2 n-Butyl acry- 98.4 49.225.0 late Methoxyethyl 49.1 49.2 25.0 acrylate 5-chloroaceto- 2 1.6 1.81.6 1.8 xymethyl- 2-norbornene The dry polymers are compounded to thefollowing recipe:

Parts Polymer Carbon black, Fast Extrusion Furnace Stearic Acid 1 Spidersulfur (sulfur dispersed with magnesium carbonate) Potassium stearateSodium stearate The compounds are cured at C for eight minutes andtempered 8 hours at C. The vulcanizates have the following physicalproperties:

raw polymer,

Pico Abrasion is run employing the testing machine and method describedin U.S. Pat. No. 2,799,155 issued July 16, 1957. It is very accurate inrating abrasion resistance of elastomers. A calibration is made using 4standard control elastomers. The average of the 4 runs is taken as 100and results on test stocks are reported in the table as a percent of thecontrol.

The improved abrasion resistance after oil immersion when a portion ofalkyl acrylate is replaced by alkoxyalkyl acrylate is shown by the data.An all alkyl acrylate material, except for the cure site monomer, (2, 3)loses at least half of its abrasion resistance after oil immersion. Thepercent change is at least 54 percent. When a portion of the alkylacrylate is replaced by alkoxyalkyl acrylate, this percent change ofabrasion resistance is improved to less than 25 percent (4), and at thesame time the excellent low temperature properties of the all alkylacrylate materials are largely retained.

When these examples are repeated with mixtures of other alkoxyalkylacrylates and mixtures thereof, including, for example, ethoxyethylacrylate and methoxyethoxyethyl acrylate with 1.5 to 5.0 parts 5-chloroacetoxy-2-norbornene, interpolymers with equivalent physicalproperties and excellent retention of abrasion resistance after oilimmersion are obtained.

These improved vulcanizable acrylic elastomers are useful inapplications where acrylic elastomers have been used in the past and areparticularly useful in oilcarrying hose applications where maintenanceof abrasion resistance after exposure to oil is highly important.

I claim:

l. A free radical catalyzed acrylate interpolymer containing polymerizedtogether 9 to 59 percent of an alkoxy alkyl acrylate represented by theformula 0 V OH CH -O-JIPO-Rl wherein R is an alkylene radical containingone to four carbon atoms and R is an alkyl radical containing one tofour carbon atoms or methoxyethoxyethyl, 40 to percent of an alkylacrylate of the formula H CHg-Jl-C 0 OR wherein R is a member of theclass consisting of alkyl groups having one to 10 carbon atoms, andcyanoalkyl groups having from two to eight carbon atoms and 0.5 to 5.5percent of an unsaturated substituted 2-hydroxymethyl-S-norbornenecompound of the formula where n is either 0 or 1, R is and R is eitherhydrogen or halogen, but if n is zero,

then R is halogen.

. The interpolymer of claim 1 wherein the alkoxy alkyl acrylate ismethoxy ethyl acrylate.

3. The interpolymer of claim 1 wherein the alkoxy alkyl acrylate Rcontains one to two carbon atoms, R contains one to two carbon atoms, Rof the alkyl acrylate contains one to four carbon atoms, and the amountof alkoxy alkyl acrylate is from 25 to about 50 percent.

4. The interpolymer of claim 1 wherein the alkoxy alkyl acrylate isethoxyethyl acrylate and the interpolymer contains 0.5 to 5.5 percent of5-chloroacetoxymethyl-2-norbornene.

5. The interpolymer of claim 1 wherein the cyanoalkyl isbeta-cyanoethyl.

6. The interpolymer of claim 1 in a vulcanized state.

7. The interpolymer of claim 4 in a vulcanized state.

UNITED STATES PATENT mirror Q TEFKCATE We QQEREQTEGN Patent No. 3,697,+9o Dated October 10, 1972 Inven (9% Philip H. Sterner It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

column line 9, that portion of the formula reading 5 H v G' 51101116. I2=&- 9 1 1.

6 line 22, that Qportion of the formula reed w should read v Signed andseaiied this 29th day of May l 973 (SEAL) Attest:

EDWARD M.FLETCHER ,JR ROBERT GO T'TSCHALK Attesting Officer Commissionerof Patents FORM K I uscoMM-Dc 60376-P69 US GOVERNMENT PRINTING OFFICE C1969 0-355-33

2. The interpolymer of claim 1 wherein the alkoxy alkyl acrylate ismethoxy ethyl acrylate.
 3. The interpolymer of claim 1 wherein thealkoxy alkyl acrylate R1 contains one to two carbon atoms, R2 containsone to two carbon atoms, R of the alkyl acrylate contains one to fourcarbon atoms, and the amount of alkoxy alkyl acrylate is from 25 toabout 50 percent.
 4. The interpolymer of claim 1 wherein the alkoxyalkyl acrylate is ethoxyethyl acrylate and the interpolymer contains 0.5to 5.5 percent of 5-chloroacetoxymethyl-2-norbornene.
 5. Theinterpolymer of claim 1 wherein the cyanoalkyl is beta-cyanoethyl. 6.The interpolymer of claim 1 in a vulcanized state.
 7. The interpolymerof claim 4 in a vulcanized state.